We theoretically consider the amplification effect on \(^3\) He-K system.
Compared to \(^{87}\) Rb magnetometer, K magnetometer has demonstrated higher sensitivity [1]}, [2]} and a \(^3\) He-\(^{39}\) K spin-based amplifier can achieve larger amplification factor as stated below. Based on the Eq. REF , we predict the amplification factor and higher magnetic sensitivity of such a spin-based amplifier. To calculate the amplification factor, we need to calculate the term \(\lambda M^{n} P^{n}_{0}\) . Using the SI units, \(\lambda M^{n} P^{n}_{0}\)  can be expressed as [3]}, [2]}
\(\begin{aligned}\dfrac{2\mu _{0}}{3} \kappa _{0} M^{n} P_{0}^{n}=\dfrac{2\mu _{0}}{3} \kappa _{0}g \mu P_{0}^{n} [\rm {N}],\end{aligned}\) 
